1. Field of the Invention
The present invention relates to a recording apparatus for forming an image on a recording sheet based on image information by a recording head.
2. Description of the Related Art
A recording apparatus forms an image on a recording sheet such as a recording paper based on image information, and is widely used as a printer, a facsimile machine, a copier, and a multifunction peripheral and system having these functions. The term “image” in the present specification is not limited to an image in its narrow sense, but includes all recordable images such as a character and a symbol, and the terms “image information” and “image data” are defined similarly in its broad sense. Recently, with rapid popularization of personal computers, the image information comes to be easily handled, and a demand for a simple recording apparatus for outputting the image information is increasing. As the recording method used in the recording apparatus, there are various methods such as an inkjet method, a laser beam method, a heat-transfer method, a thermal method, and a wire-dot method. Among these methods, the recording apparatus adopting the inkjet method is relatively compact and inexpensive, and moreover, enables realizing highly refined recording.
Particularly in the inkjet recording apparatus, in a case where a recording head is mounted on a carriage, ink discharge in a recording operation has to be performed within a scanning range of the carriage. However, in a case where the recording sheet set in the apparatus is smaller than the scanning range of the carriage, and the recording data is set that exceeds a size of the recording sheet, the ink is discharged beyond a width of the recording sheet.
In such a situation, there arises a problem in that ink smears the inside of the apparatus, which smears the subsequent recording sheet or the hands of the user who operates the apparatus. Further, recording time is uselessly spent by the movement of the carriage which is unnecessary for the recording operation, so that throughput is reduced. In order to avoid such problem, a width of the recording sheet is detected. For example, Japanese Patent Application Laid-Open No. 4-158078 discusses a technique in which a reflective sensor is provided on the carriage and the carriage is moved over the sheet in the width direction from end to end to detect the change of the sensor output, so that the width of the recording sheet can be determined.
However, according to the above conventional technique in which the sheet width is detected by the sensor mounted on the carriage, the following problems arise. First, a wide area on the recording sheet has to be scanned, and thus it takes a long time to complete the detection, which reduces throughput. Second, there is a problem in that it is impossible to detect the sheet width unless the recording sheet is fed, and accordingly the technique cannot be utilized in a printer driver configured to form the image information before starting the sheet feeding.